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Marler Blog Providing Commentary on Food Poisoning Outbreaks & Litigation

Contaminated Flour – Something else to worry about?

Yesterday’s announcement from Nestle that it had “informed the FDA [on January 11, 2010] that two samples of Nestle Toll House refrigerated cookie dough … had tested positive for E. coli O157:H7…,” came as both a shock, that sick months after a severe E. coli O157:H7 outbreak, product was testing positive again, and a wake up call that clearly more needs to be done to make the product safe. The good news is that according to Nestle, “[c]onsistent with [its] quality assurance protocol, the finished product involved never left [its] factory or entered the supply chain, and none was shipped to customers.

Clearly, Nestle by also announcing that it “will [now] begin using heat-treated flour in the manufacture of its Nestle Toll House refrigerated cookie dough,” shows its desire to lead the industry by making one of its key ingredients (flour) safer for human consumption. It does, however, raise some interesting issues that Nestle will need to respond to.

1.  What did Nestle (and the entire flour industry) know about the risk that uncooked flour can be contaminated with a pathogen? Interesting, that discussion has been going on over at the FoodSafe Listserve both yesterday and today. Some cited examples of prior studies can be found below.

2.  What testing protocols did Nestle use on cookie dough ingredients after June 2009 and what were the test results? Being an industry leader requires transparency.

3.  When did Nestle make the decision to consider heat-treated flour?  Why?  Did it take time to reformulate recipe?

4.  With respect to the two samples of Nestle Toll House refrigerated cookie dough that tested positive for E. coli O157:H7, were those sample (including PFGE analysis) provided to the FDA and CDC? Again, being an industry leader requires transparency.

How do you say “leadership” and “transparency” in Swiss?

GMA: Control Of Salmonella In Low-Moisture Foods February 4, 2009. . . Raw materials used to manufacture low-moisture products, such as spices, raw cocoa beans, raw nuts, raw peanuts, flour and cereal grains, may be a potential source of Salmonella. Surveys reported the incidence of Salmonella in wheat flour ranged from 0.14% to 1.32% (Sperber et al., 2007), . . .

AU: Richter,-K.S.; Dorneanu,-E.; Eskridge,-K.M.; Rao,-C.S. TI: Microbiological quality of flours. SO: Cereal-Foods-World. St. Paul, Minn. : American Association of Cereal Chemists. May 1993. v. 38 (5) p. 367-369. PY: 1993 IS: ISSN: 0146-6283 AB: Over 4,000 wheat flour samples were tested according to FDA/BAM methods for Salmonella and Escherichia coli in addition to yeast and mold, aerobic plate count (APC), and coliform most probable number (MPN) counts. The data were analyzed statistically based on flour type-hard red winter (HRW), soft red winter (SRW), spring (SPG), or durum (DUR)-and season of milling production. SRW had the highest mold count (log10 3.06 cfu/g) and DUR the lowest (log10 2.85 cfu/g). SPG had the highest yeast count (log10 2.27 cfu/g) and SRW the lowest (log10 2.07 cfu/g). Highest APCs were found in DUR (log10 4.24 cfu/g), whereas the lowest were in SRW (log10 3.83 cfu/g). Of the samples tested, 12.8% were E. coli positive and 1.3% were Salmonella positive with the highest frequency of each pathogen occurring in the fall and winter months, respectively. The lowest E. coli frequency occurred during spring, whereas Salmonella had the lowest incidence in summer. The highest percentage of E. coli positives was observed in DUR (17%), and the lowest was observed in HRW samples (6.7%). The highest percentage of Salmonella positives existed in SRW (2.3%) and the lowest in DUR flour samples (0.3%). From the data, 95% confidence limits of 5,700 cfu/g for mold, 110,000 cfu/g for APC, and 150 MPN/g for coliforms were determined for all wheat flours.

TI: Microbiology of wheat and flour milling in Australia. AU: Berghofer,-Lana-K [Author]; Hocking,-Ailsa-D [Author,-Reprint-Author]; Miskelly,-Di [Author]; Jansson,-Edward [Author] SO: International-Journal-of-Food-Microbiology. 2003; 85(1-2): 137-149 PY: 2003 IS: 0168-1605 AB: A survey was undertaken to determine the microbiological status of Australian wheat and the distribution of microorganisms in the flour milling fractions and end products. A total of 650 milling process and end product samples was obtained from nine flour mills located in New South Wales (4), Queensland (2), Victoria (2) and Western Australia (1) during the 1997-1998 and 1998-1999 wheat seasons. Most frequent (modal) counts in wheat and flour were, respectively, as follows: aerobic mesophilic plate count, 105 and 102 colony forming units/gram (cfu/g); coliforms, 10 and 1 most probable number/gram (MPN/g); Bacillus spp., 104 and 102 cfu/g; B. cereus, 1 and 0.1 MPN/g; mesophilic aerobic spores, 10 and 1 cfu/g; aerobic thermophiles, both 10 cfu/g; yeasts, 103 and 102 cfu/g, and moulds, 103 and 102 cfu/g. Bacillus spp., coliforms, yeasts and moulds were the most frequently detected microorganisms throughout the survey. The most common moulds isolated were Aspergillus, Penicillium, Cladosporium and Eurotium spp. Environmental serovars of Salmonella were isolated from two samples. Escherichia coli and B. cereus were present at very low levels, a majority of positive samples being at the minimum level of detection (3 and 0.3 MPN/g, respectively). As wheat grain layers are separated, surface-adhering contaminants are concentrated in end product bran, wheat germ and pollard, which comprise the outer layers of the gain. Consequently, the inner endosperm fraction contains lower microbial counts, and flour is the cleanest end product of the milling process. Higher microbiological counts midstream in the milling process indicate that equipment contamination may contribute to microbiological contamination; however, the microbiological quality of incoming wheat has a strong influence on the ultimate quality of milling end products.

TI: [Microbiological analysis of 40 samples of corn (Zea mais) and derived products obtained from retail sources in Barcelona, Spain.] AU: Anaya,-I; Ventura,-M; Comellas, L; Agut,-M SO: Alimentaria. 2004; (354): 73-79 ; 5 ref. AB: Microbiological quality of 40 samples of corn (maize) and corn products obtained from retail sources in Barcelona, Spain, was assessed. Products studied included corn on the cob, sweetcorn, popcorn, microwave popcorn, fried corn, corn flour, corn-based pancakes and split corn for animal feed. The samples were tested for aerobic mesophiles, coliforms, Escherichia coli, Salmonella, Shigella, Staphylococcus aureus, Bacillus cereus and yeasts and other fungi. All samples of sweetcorn , popcorn and corn flour complied with Spanish regulations. Some samples of the other products did not comply with these regulations. 1 sample of microwave popcorn contained Salmonella enterica. 1 sample of corn pancakes and 2 samples of fried corn slightly exceeded the Spanish tolerance for the yeast and other fungi count.

TI: Review of studies on the thermal resistance of salmonellae. AU: Doyle,-M-E; Mazzotta,-A-S SO: Journal-of-Food-Protection. 2000; 63(6): 779-795 ; many ref. AB: Heat resistance data for different serotypes of Salmonella enterica in different foods and laboratory media are reviewed. Aspects considered include: heat resistance of salmonellae in different foods (eggs, milk and dairy products, poultry and other meats, chocolate, wheat flour, corn flour, corn-soymilk blends, shellfish, coconut, pecans, alfalfa seeds, and other foods); and effects of different parameters on heat resistance of salmonellae in culture media (type of culture media, recovery procedures, high sugar concn., high salt concn., drying, sublethal heatshock, other temp. effects, pH, exposure to the lactoperoxidase system, competitive microflora, surface attachment, chelating agents, other food additives, and other conditions (such as low carbohydrate levels, irradiation and high hydrostatic pressure)).

TI: Bacteriological survey of sixty health foods. AU: Andrews,-W-H; Wilson,-C-R; Poelma,-P-L; Romero,-A; Mislivec,-P-B SO: Applied-and-Environmental-Microbiology. 1979; 37(3): 559-566 ; 16 ref. DT: Journal-Article PY: 1979 AB: A bacteriological survey was performed on 1960 food samples encompassing 60 types of health foods available in the Baltimore-Washington, DC, metropolitan area. No consistent bacteriological distinction (aerobic plate counts, total coliform and faecal coliform MPN) was observed between foods labelled as organic (raised on soil with compost or nonchemical fertilizer and without application of pesticides, fungicides and herbicides) and their counterpart food types bearing no such label. Types and numbers of samples containing Salmonella were: sunflower seeds, 4; soy flour, 3; soy protein powder, 2; soy milk powder, 1; dried active yeast, 1; brewers’ yeast, 1; rye flour, 1; brown rice, 1; and alfalfa seeds, 1. The occurrence of this pathogen in 3 types of soybean products should warrant further investigation of soybean derivatives as potentially significant sources of Salmonella.

  • Marymary

    Very interesting, but how do you get from Salmonella and bacillus cereus in flour to E.coli O157:H7? And why is Nestlé focusing on heat treating flour as a preventive step? Have they determined that no other ingredient, including water used at its plants, could be responsible?
    By the way,I’m not expert on Switzerland, but I believe that there are four official languages, German, French, Italian, and Romanche (sp?). Other languages/dialects (such as Swiss German) are spoken there, but those are the official ones. Nestl√© likely originated in the French-speaking part of the country, so whatever you have to say, it is probably best to stick to French–or English! :)